<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .father {
            width: 300px;
            height: 300px;
            background-color: pink;
            margin: 100px auto;
        }

        .son {
            width: 200px;
            height: 200px;
            background-color: purple;
        }
    </style>
</head>

<body>
<div class="father">
    <div class="son"></div>
</div>
<script>
    var father = document.querySelector('.father');
    var son = document.querySelector('.son');
    father.addEventListener('mouseenter', function () {
        console.log(11);

    })
</script>
</body>

</html>
